This study will further understanding of the basic biology of urinary bladder tumors and provide a cytochemical foundation for improvements in exfoliated cell diagnostic cytology. Dibutylnitrosamine-induced rat bladder tumors will serve as an experimental model. Cells exfoliated during carcinogenesis will be characterized cytochemically, with emphasis on differentiating normal and early-stage neoplastic cells. The temporal acquisition of cytochemical changes will be related to bladder pathology, conventional diagnostic cytology, and carcinogenic protocol. Quantitative cytochemical measurements of alkaline phosphatase, 5-nucleotideases, cathepsin B, dipeptidyl aminopeptidases, and other proteases and esterases will be made. Membrane differences will be identified using fluroescamine and lectin binding. Measurements will be made using both static and flow fluorometers and, when appropriate, comparison will be made with human cell samples to determine the diagnostic value of the various rat-tumor markers.